[PATCH 6.1 560/609] fortify: refactor test_fortify Makefile to fix some build problems

Greg Kroah-Hartman <[email protected]>
Newsgroups dev.linux.lists.patches,org.kernel.vger.stable
Message-ID <[email protected]>
6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Masahiro Yamada <[email protected]>

commit 4e9903b0861c9df3464b82db4a7025863bac1897 upstream.

There are some issues in the test_fortify Makefile code.

Problem 1: cc-disable-warning invokes compiler dozens of times

To see how many times the cc-disable-warning is evaluated, change
this code:

  $(call cc-disable-warning,fortify-source)

to:

  $(call cc-disable-warning,$(shell touch /tmp/fortify-$$$$)fortify-source)

Then, build the kernel with CONFIG_FORTIFY_SOURCE=y. You will see a
large number of '/tmp/fortify-<PID>' files created:

  $ ls -1 /tmp/fortify-* | wc
       80      80    1600

This means the compiler was invoked 80 times just for checking the
-Wno-fortify-source flag support.

$(call cc-disable-warning,fortify-source) should be added to a simple
variable instead of a recursive variable.

Problem 2: do not recompile string.o when the test code is updated

The test cases are independent of the kernel. However, when the test
code is updated, $(obj)/string.o is rebuilt and vmlinux is relinked
due to this dependency:

  $(obj)/string.o: $(obj)/$(TEST_FORTIFY_LOG)

always-y is suitable for building the log files.

Problem 3: redundant code

  clean-files += $(addsuffix .o, $(TEST_FORTIFY_LOGS))

... is unneeded because the top Makefile globally cleans *.o files.

This commit fixes these issues and makes the code readable.

Signed-off-by: Masahiro Yamada <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>
[nathan: Fixed conflicts]
Signed-off-by: Nathan Chancellor <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
 lib/.gitignore              |  2 --
 lib/Makefile                | 34 +---------------------------------
 lib/test_fortify/.gitignore |  2 ++
 lib/test_fortify/Makefile   | 28 ++++++++++++++++++++++++++++
 scripts/remove-stale-files  |  2 ++
 5 files changed, 33 insertions(+), 35 deletions(-)
 create mode 100644 lib/test_fortify/.gitignore
 create mode 100644 lib/test_fortify/Makefile

diff --git a/lib/.gitignore b/lib/.gitignore
index 54596b634ecbf..101a4aa92fb53 100644
--- a/lib/.gitignore
+++ b/lib/.gitignore
@@ -5,5 +5,3 @@
 /gen_crc32table
 /gen_crc64table
 /oid_registry_data.c
-/test_fortify.log
-/test_fortify/*.log
diff --git a/lib/Makefile b/lib/Makefile
index 6ae66e13f3194..1081d0c161159 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -394,36 +394,4 @@ CFLAGS_longest_symbol_kunit.o += $(call cc-disable-warning, missing-prototypes)
 
 obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o
 
-# FORTIFY_SOURCE compile-time behavior tests
-TEST_FORTIFY_SRCS = $(wildcard $(srctree)/$(src)/test_fortify/*-*.c)
-TEST_FORTIFY_LOGS = $(patsubst $(srctree)/$(src)/%.c, %.log, $(TEST_FORTIFY_SRCS))
-TEST_FORTIFY_LOG = test_fortify.log
-
-quiet_cmd_test_fortify = TEST    $@
-      cmd_test_fortify = $(CONFIG_SHELL) $(srctree)/scripts/test_fortify.sh \
-			$< $@ "$(NM)" $(CC) $(c_flags) \
-			$(call cc-disable-warning,fortify-source) \
-			-DKBUILD_EXTRA_WARN1
-
-targets += $(TEST_FORTIFY_LOGS)
-clean-files += $(TEST_FORTIFY_LOGS)
-clean-files += $(addsuffix .o, $(TEST_FORTIFY_LOGS))
-$(obj)/test_fortify/%.log: $(src)/test_fortify/%.c \
-			   $(src)/test_fortify/test_fortify.h \
-			   $(srctree)/include/linux/fortify-string.h \
-			   $(srctree)/scripts/test_fortify.sh \
-			   FORCE
-	$(call if_changed,test_fortify)
-
-quiet_cmd_gen_fortify_log = GEN     $@
-      cmd_gen_fortify_log = cat </dev/null $(filter-out FORCE,$^) 2>/dev/null > $@ || true
-
-targets += $(TEST_FORTIFY_LOG)
-clean-files += $(TEST_FORTIFY_LOG)
-$(obj)/$(TEST_FORTIFY_LOG): $(addprefix $(obj)/, $(TEST_FORTIFY_LOGS)) FORCE
-	$(call if_changed,gen_fortify_log)
-
-# Fake dependency to trigger the fortify tests.
-ifeq ($(CONFIG_FORTIFY_SOURCE),y)
-$(obj)/string.o: $(obj)/$(TEST_FORTIFY_LOG)
-endif
+subdir-$(CONFIG_FORTIFY_SOURCE) += test_fortify
diff --git a/lib/test_fortify/.gitignore b/lib/test_fortify/.gitignore
new file mode 100644
index 0000000000000..c1ba37d14b50e
--- /dev/null
+++ b/lib/test_fortify/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+/*.log
diff --git a/lib/test_fortify/Makefile b/lib/test_fortify/Makefile
new file mode 100644
index 0000000000000..7887e6126e79c
--- /dev/null
+++ b/lib/test_fortify/Makefile
@@ -0,0 +1,28 @@
+# SPDX-License-Identifier: GPL-2.0
+
+ccflags-y := $(call cc-disable-warning,fortify-source)
+
+quiet_cmd_test_fortify = TEST    $@
+      cmd_test_fortify = $(CONFIG_SHELL) $(srctree)/scripts/test_fortify.sh \
+			$< $@ "$(NM)" $(CC) $(c_flags) -DKBUILD_EXTRA_WARN1
+
+$(obj)/%.log: $(src)/%.c $(srctree)/scripts/test_fortify.sh \
+	      $(src)/test_fortify.h \
+	      $(srctree)/include/linux/fortify-string.h \
+	      FORCE
+	$(call if_changed,test_fortify)
+
+logs = $(patsubst $(srctree)/$(src)/%.c, %.log, $(wildcard $(srctree)/$(src)/*-*.c))
+targets += $(logs)
+
+quiet_cmd_gen_fortify_log = CAT     $@
+      cmd_gen_fortify_log = cat $(or $(real-prereqs),/dev/null) > $@
+
+$(obj)/test_fortify.log: $(addprefix $(obj)/, $(logs)) FORCE
+	$(call if_changed,gen_fortify_log)
+
+always-y += test_fortify.log
+
+# Some architectures define __NO_FORTIFY if __SANITIZE_ADDRESS__ is undefined.
+# Pass CFLAGS_KASAN to avoid warnings.
+KASAN_SANITIZE := y
diff --git a/scripts/remove-stale-files b/scripts/remove-stale-files
index ccadfa3afb2b8..c22fe4630bac0 100755
--- a/scripts/remove-stale-files
+++ b/scripts/remove-stale-files
@@ -47,3 +47,5 @@ rm -f arch/riscv/purgatory/kexec-purgatory.c
 rm -f scripts/extract-cert
 
 rm -f arch/x86/purgatory/kexec-purgatory.c
+
+rm -f lib/test_fortify.log
-- 
2.53.0
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